Ответ:

  1. 9 999 + 1 = 10 000
  2. 56 999 + 1 = 57 000
  3. 62 889 + 1 = 62 890
  4. 23 000 − 1 = 22 999
  5. 3 599 + 1 = 3 600
  6. 1 579 + 1 = 1 580
  7. 4 200 − 1 = 4 199
  8. 5 000 − 1 = 4 999